1. Field of the Invention
The embodiments of the present invention relate generally to a filter housing assembly and leak testing thereof.
2. Background of the Invention
Cleanrooms are utilized in many industries for contamination control and to improve product yields. A plurality of filters, typically mounted in the ceiling of the cleanroom, are configured to remove particulates from air entering the cleanroom at a predetermined efficiency selected based upon the cleanliness requirements of the activities performed in the cleanroom. As particulates load the filtration media disposed in the filter, the airflow through the filter decreases as the pressure drop across the filter increases. Once the filter reaches a critical pressure drop, the filter is typically replaced.
On other applications, replacement of filters is scheduled based on time or processes performed within the cleanroom. For example, in many pharmaceutical and biotech cleanrooms, periodic replacement of filters is required to meet regulatory or owner specifications. To facilitate efficient replacement of the filter, a ducted supply hood is typically mounted in the cleanroom ceiling in which the filter may be readily removed and replaced from the cleanroom side of the ceiling.
In many applications, the installed replacement filter must be leak tested before normal cleanroom activities may commence. In order to perform a statistically valid leak test within a reasonable time period, an aerosol challenge is introduced into the hood upstream of the filter. To this end, these hoods are equipped with ports accessible from the clean room for injecting an aerosol challenge into the upstream plenum of the hood to facilitate testing.
Since the aerosol injection port is coupled to an aerosol generator during testing of the filter, leakage through the port cannot be tested during re-testing of the filter. Once the aerosol generator is removed and the aerosol injection port sealed, there is typically not enough challenge remaining in the plenum within the hood to enable reliable testing of the sealed port.
Therefore, there is a need for a ducted hood, i.e., a housing assembly, and a technique to facilitate testing of aerosol injection ports.